TFS · Hydraulic & Fluid Applications · Problem 59PDFSolution in PDF ↓
TFS · Hydraulic & Fluid Applications · Problem 59
Problem & Solution
Video Synthesis
- Problem: Congrats on reaching the end of the Fluids chapter.
- Key values: 90 %, 50 gpm, 15 psi, 5 psi
- Reference: Darcy
- Result: That's why we did this little translation and then we can say Q a plus This quantity 0.689 times Q a equals 50 g p n and now we combine like terms on ...
- ✅ Answer: A
Office Hours
2
Student questions asked in live office hours about this problem
OH 80
Q: Since the pipe diameter wasn't given in this parallel piping problem, why isn't it viable to arbitrarily select a diameter (like 2 inches) and proceed with the calculation?
A: Assuming a specific diameter creates a problem downstream because it locks in an area value, which then determines velocity for a given flow rate through Q=VA. If your assumed diameter is wrong, the velocity will be wrong, and you won't be able to satisfy the constraint that QA + QB must equal the total flow of 50 GPM when the flows recombine. Instead, you should abstract out both diameter and velocity by deriving a relationship between velocity ratios and linear feet, which lets you solve the problem without assuming a specific pipe size.
OH 96
Q: In the parallel branch problem, why convert the pressure drop from the coil and control valve into equivalent length and add it to the Darcy equation, rather than simply equating the total pressure drops across both branches?
A: It does look odd at first, but this method is legitimate—pressure drop can always be converted to head using ΔP = ρgh or γh, giving you feet that go into the Darcy equation. I modeled it after established problems, so while it feels strange to put pressure-derived feet into the pressure loss formula, it's a valid approach that works.